Vulcanization accelerator



Patented July 27, 1943 I ver Lake, Ohio, assignors to The B. F. GoodrichCompany, New York, ;N, Y,.,-a cotporafiiqno New York Y N This inventionrelates to the vulcanization of rubber and pertainsspeciflcallyto theaccelera' tion of vulcanization by the disulfides formed'by reacting ametallic salt of the.2-me'rcapto thiazolines with the nitro phenylsulfurhalides'.

It is well known that the vulcanization of rubber may be acceleratedby'the presence of vari-' ous compounds;'notably sulfur-containing com-'pounds, in the rubber composition. It has also been reported in theliterature that; the 2-mercapto thiazolines, although similar instructure to the j2.-mercap'to .thia'zoles, which are excel; lent.accelerators, arenevertheless weakaccelerators themselves. However, in aco-pendingjjap plication Serial No; 255,358, filed February 3,.

1939,. we have. disclosed that z me'rcapto thiazolines in combinationwith monocarboxylic acids are good accelerators We, have new discoveredthat the .thiaz olinyl nitro-ary l -disulfides, in on junction withmonocarboxylic acids, saturated or,

unsaturated, or metallic salts, when used as accelerators in rubbercompositions give stocks with good elongation and tensile strengthcharacteristics.

The thiazolines which may be used for the synthesis of our newaccelerators may be substituted in a variety of ways, comprising suchcom-' pounds as 2-mercapto thiazoline, Z-mercapto 4- methyl thiazoline,2-mercapto 4,5-dimethyl thiazoline, Z-mercapto 4-ethyl thiazoline,Z-mercapto 5-ethyl thiazoline, Z-mercapto 4,5-diethyl thiazoline,2-mercapto lg-P118113 1 thiazoline, Z-rnercapto 4-methoxy thiazoline,2-mercapto 4,5-tetramethylene thiazoline, and the like. We prefer to usean alkali metal salt of such a mercaptan in the synthesis. of our newcompounds. The other compound used in the synthesis, a nitro aryl sulfurhalide, may also contain varioussubstituent groups. Such compounds asp-nitro phenyl sulfur chloride, o-nitro phenyl sulfur chloride,2-benzoy1 4-nitro phenyl sulfur chloride, etc., or the correspondingbromides are satisfactory.

The best results are obtained with this type of accelerator, we havefound, when it is used in conjunction with a saturated or unsaturatedmonocarboxylic acid, such as caprylic, -lauric, oleic, stearic,linoleic, palmitic, benzoic, salicylic, and the like. Mere traces ofsuch acids are effective activators for our accelerator, but we preferto use from 1% to 5% or-more inthe rubber composition. The tin, lead,zinc, calcium, sodium, or other alkali, alkaline earth, or heavy metalsalts of the above acids may be used as the activator in about the sameamount.

imputation December 24, 1940, I I I setial'No. 371,578

As a specific example of, our invention we a have prepared2-thiaz'olinyl o-nitrophenyl disulfide as shown the following reaction:

I '.No, q A solution of .14.? g. of o-nitropl'lenyl sulfur chlo- Withstirring to alsolutiofiflof 9.25 g. of Z-mercapto thiazoline and 3.4g.of sodium hydroxide I in 100 ml. of water at room temperature. The

' jfU'sing this product cce ,at r, the

lou'ringc'ompo'sition was pre ared:

Rubber I I I 100 Zincoxide 5 Sulfur 3 Lauricar-id I 3 2 -thiazolinylo-nitrophehyl disulfide I 30 WhenIcured in a mold at 287 F..for theindicated length of timethe stock produced had the following properties,where T is tensile strength in'pound's per square inch and E -iselongation in percent: 3o 7 Time of cure, min, T I E These results showthe activity of ournew type of accelerators.

Our new accelerators are effective not only with natural rubber orcaoutchouc, but also with balata, vgutta percha, latex, rubber isomers,or any synthetic rubber which can be vulcanized, that is, which losesits property of thermoplastici ty and becomes elastic when heated in"the used in the claims to designate all of the abovementioned materials.Other materials, such as pigments, fillers, reinforcing agents,softeners, antioxidants, other accelerators, etc., may be so used in thecomposition. I

ride in mL-of methanol was added slowly product, in the form of finecrystals, was filtered I v i from the reactipn mixture Iand .washedwithwa-r.

ter. '"A 713% 'jjyieldo'f a" Ir'nateri'al melting at 1 presence ofsulfur and the termfa rubber is The rubber stocks produced with ouraccelerators are not limited in their uses, being applicable to themanufacture of pneumatic and solid rubber tires, hose,belting, footwear,surgical goods, latex-dipped goods, all manner of molded articles, andthe like. n

v Any of the ufsual m'ethodslbt ,Vulcanization',

1 such as heating in a mold, in hot air, steam, hot

water, etc. are suitable.

' Although we have herein disclosed specific em bodiments of ourinvention, we do not intend to limit ourselves solely thereto but onlytofthe spirit and scope of the appended'claims. u' c t We claim: 5

1. The process of vulcanizing arubber in the presence of a compoundhaving the structure J J. R I H inwhich R1, R2, R3, and R4 are membersfof the class consisting of :hydrogen; hydrocarbon and alkyl ethergroups; and in the presence of a o-s s-(nitmpi n n member of the classconsisting of monocarboxylic acids and their metallic salts.

2. 'I he process of vulc'a'niaing a rubber in the presence of acompound'hayingthe structure in, which R1, .Rzf-Rs, and .arefmembers'of;the class consisting. of hydrogen; hydrocarbon, and alkyl ether groups;and in'thej presence of amem 'ber of thdclass', consisting ofmonocarboxylic acids and their metallic salts.

,325,259 v "if.

3. The process of vulcanizing a rubber in the presence of 2-thiazolinylo-nitrophenyl disulfide and a member of the class consisting ofmonocarboxylic acids and their metallic salts. 4. A compositioncomprising a rubber vulcanized in the presence of a compoundhaving thein R1, R3, and R4 are members of the class consisting of hydrogen,hydrocarbon, and

lzjl'all nl ether groups; and in the presence of a member of the classconsisting of monocarboxyli 1, acids and their metallic salts.

A. composition comprising 'a rubber .vulcanizedfin the presence, of a;compound having the structuiie. m "f

